Additive manufacturing (AM) is used to create geometries otherwise impossible to machine. Topology optimization, microstructural texture control, and the use of lattices could be created through AM to increase performance of systems. Currently research focuses on solution aging of printed 17-4 PH, while other heat treatments are not as heavily studied. This study identifies different heat treatments applied to additively manufactured 17-4 precipitation hardened (PH) and the effects on mechanical properties. This study used quasi-static tension, quasi-static compression, and Charpy V-notch testing to analyze the effects of heat treatment as well as the effectiveness of additive manufacturing compared to traditional machining for wrought materials. Data during testing was taken with digital image correlation to identify changes in local strain. The effectiveness of heat treatment was demonstrated in this study and can be used to estimate performance on additively produced 17-4 PH.

<p>Polymer nanocomposites are a constantly evolving material category due to the ability to engineer the mechanical, thermal, and optical properties to enhance the efficiency of a variety of systems. While a vast amount of research has focused on the physical phenomena of nanoparticles and their contribution to the improvement of such properties, the ability to implement these materials into existing commercial or newly emerging processing methods has been studied much less extensively. The primary characteristic that determines which processing technique is the most viable is the rheology or viscosity of the material. In this work, we investigate the processing methods and properties of nanocomposites for thermal interface and radiative cooling applications. The first polymer nanocomposite examined here is a two-component PDMS with graphene filler for 3D printing via a direct ink writing approach. The composite acts as a thermal interface material which can enhance cooling between a microprocessor and a heat sink by increasing the thermal conductivity of the gap. Direct ink writing requires a shear thinning ink with specific viscoelastic properties that allow for the material to yield through a nozzle as well as retain its shape without a mold following deposition. No predictive models of viscosity for nanocomposites exist; therefore, several prominent models from literature are fit with experimental data to describe the change in viscosity with the addition of filler for several different PDMS ratios. The result is an understanding of the relationship between the PDMS component ratio and graphene filler concentration with respect to viscosity, with the goal of remaining within the acceptable limits for printing via direct ink writing. The second nanocomposite system whose processability is determined is paint consisting of acrylic filled with reflective nanoparticles for radiative cooling paint applications. The paint is tested with both inkjet and screen-printing procedures with the goal of producing a thermally invisible ink. Radiative cooling paint is successfully printed for the first time with solvent modification. This work evaluates the processability of polymer nanocomposites through rheological tailoring. </p><br>

Electroactive polymers are a class of materials capable of reallocating their shape in response to an electric field while also having the ability to harvest electrical energy when the materials are mechanically deformed. Electroactive polymers can therefore be used as sensors, actuators, and energy harvesters. The parameters for manufacturing flexible electroactive polymers are complex and rate limiting due to number of steps, their necessity, and time intensity of each step. Successful additive manufacturing processes for electroactive polymers will allow for scalability and flexibility beyond current limitations, advancing the field, opening additional manufacturing possibilities, and increasing output. The goal for this research was to use additive manufacturing techniques to print conductive and dielectric substrates for building flexible circuits and sensors. Printing flexible conductive layers and substrates together allows for added creativity in design and application.

WAAM is a relatively unexplored additive manufacturing method. Although research in this area has been performed for some years and the hardware is relatively cheap, the method is not widely used. As the name suggest, it uses wire and an arc welding equipment to deposit beads on top of each other to create a geometry. As WAAM is a near net-shape method, the parts must be machined to its net-shape after the beads has been deposited. BAE Systems Hägglunds AB are investigating the use of WAAM in an industrial robot cell and this Master’s thesis has been written with the purpose of enabling the use of WAAM for manufacturing parts at the company. This report investigates how a part is prepared for WAAM and near net-shape machining. A formula for approximating the cost of manufacturing a part is investigated. A software for slicing a .STL file for generating a toolpath is developed in Matlab. The software then exports the toolpath to a code that the robot can read. It can also generate a digital model of the work piece for net-shape machining through CATIA macro. A model for calculating the cost of using the WAAM-cell once the toolpath for a part is known is presented. The investigated areas and the developed software are then applied to a part, and the results of the report is discussed.

3DP (three-dimensional printing) technologies have become more than just a tool to help companies with prototyping and designing in the pre-production stage. Some firms have already implemented 3DP technology to produce parts and end-use products. However, there are several challenges and barriers that this technology must overcome to replace traditional manufacturing methods. One of the most significant obstacles associated with 3D printing is its low level of accuracy in variable repeatability when it comes to making separate batches of the same product. There are several arguable reasons behind this variation. Some of the factors that can influence repeatability are the type of material, the design, the type of product produced, and the orientation, or the location of the build inside the building envelope. The goal of this study was to determine whether the location of the build inside the surface area of the working envelope can affect the properties (height, width, depth, and weight) of the product. Western Kentucky University (WKU) provides students with a few 3D printers on campus. One of those printers, a Stratasys (model: BST 768/SST 768), is in the Senator Mitch McConnell Advanced Manufacturing and Robotics Laboratory. The researcher used this printer for the study to determine if the location of the printer influenced the final product. The conclusion of the research did reveal that the printing location does affect the quality of the final product.

Subtractive manufacturing are the most common methods in the aerospace industry to manufacture components. In these parts the buy to fly ratio is low and it needs accurate strengths analyses to static and dynamic loads especially were the different parts relate to each other with fasteners in the assembly work. Additive manufacturing has now been developed to be of such quality that the aerospace industry see the potential to use the technology in their production of parts. It has been possible to make them lighter, stronger and reduce the total amount of parts in an assembly. This mean probably some changes to the stakeholders in the process of their product development. Engineers who are working on the products will need to face the design aspects and restrictions with AM to choose the right component/sub-assemblies to convert to AM parts. This thesis will address the possibility to redesign a wing rudder and to get some knowledge about the engineer’s point of view of AM and how it may affect them. Today there are several aerospace industries adopting AM and get airworthy components to less critical parts as brackets but also parts in the engines as the fuel nozzle in an Airbus (Trimble, 2016). For larger parts, there have also been studies to use AM for example internal galley partition but the result is it will take too long time to print by todays machines. There are several different methods for AM and Powder Bed System is popular in the aerospace industry according to its geometrical correctness to the CAD model (Dordlofva, Lindwall, &amp; Törlind, 2016). Commercial aircrafts industry starts to get harder regulations for their emissions to get lighter planes and less air resistance. AM open up the possibilities to meet these requirements by producing parts which was impossible to produce before. The design process for AM design today are not fully known yet, which leave a lot to imagination. There are general design rules on how to design for AM build but it does not necessary mean the part will be correctly built. There are several cost driven aspects with AM, the most expensive part is the print time but there are different aspects to. For example, CNC machining may be needed after the AM build and add cost for subtractive manufacturing. Interviews with engineer’s groups have been made to conduct their thoughts and knowledge of AM and how it may affect their work. Some uncertainties were mentioned and it was most focused on the process and the reliability of the finished part. The engineers think the design process will be almost the same and only change boundary conditions. To get ideas, a workshop was made with some design guidelines for development of different designs on the wing rudder and to bring positive and negative aspects to the design. An overall cost calculation was made for a few parts and the result shows that it is hard to compete with the design of the wing rudder today. The most important aspects for a success of AM is the print speed, qualified manufacturing processes and CAD software support for the engineers. / Flygindustrin använder sig främst av subtraktiv bearbetning i sin framställning av de olika komponenterna till ett flygplan. Det blir då ofta en väldigt låg grad av materialutnyttjande, endast några procent återstår av det inköpta utgångsmaterialet. Till det tillkommer monteringsarbete och noggranna hållfasthetsanalyser, både statisk och utmatningshållfasthet av sammanbyggda skarvar där fästelement är en del. Den additiva tillverkningen har nu utvecklats och visat sig inneha kvalitéer för att klara kraven som ställs i flygindustrin. Det kan göra detaljerna lättare, starkare och minska antalet komponenter i monteringsarbetet. Det kan innebära en hel del förändringar för olika intressenter som får börja tänka annorlunda. Ingenjörer som arbetar med produktframtagning kommer att ställas inför utmaningen att applicera denna teknik på lämpliga delar/delkonstruktioner. Detta examensarbetet undersöker möjligheten att designa ett vingroder till ett flygplan och bilda en uppfattning om ingenjörernas förtroende för additiv tillverkning samt hur det kommer påverka dem. Det finns idag flera flygindustrier som har påbörjat att ta fram flygvärdiga komponenter, framförallt mindre kritiska fästelement men även en del artiklar i motorer så som bränslemunstycke hos Airbus (Trimble, 2016). De har analyserat möjligheten att använda additiv tillverkning på större artiklar såsom inre kabinstruktur men har kommit fram till att det tar för lång tid att tillverka med dagens maskiner. Det finns flertalet olika additiva tillverkningsmetoder men den som står ut är pulverbäddskrivaren då den har en bättre geometrisk korrekthet gentemot CAD modellen (Dordlofva, Lindwall, &amp; Törlind, 2016). Nya reglementen för utsläpp i den komersiella flygindustrin pressar företagen att bygga bättre flygplan som är lättare och därmed får mindre luftmotstånd. Designprocessen för additiv tillverkning är inte given då det inte finns några givna processer som täcker hela processen. Det finns generella design-riktlinjer i vad de olika maskinerna klarar av att bygga, men samtidigt är det ingen garanti att genom att följa dessa riktlinjer skapa en fungerande design. Det finns flera olika kostnadsdrivande aspekter med additiv tillverkning. Det som mest driver kostnaden idag är den låga skrivarhastigheten. Andra kosnadsdrivare är om det tillkommer efterarbete för att uppfylla toleranser eller få en korrekt / plan sammanfogningsyta. Arbetet har utförts med intervjuer av ingenjörsgrupper för att skapa en uppfatting om deras syn på additiv tillverkning och hur det skulle ändra deras arbete. En viss osäkerhet förekom men det berodde framförallt på osäkerheten för säkring av processen, dvs tillverkningsprocessen och att kunna vara säker på att detaljen håller måttet. De ansåg att designprocessen inte skulle förändras så mycket, utan bara att randvillkoren skulle ändras. Utifrån workshops och designriktlinjer har koncept tagits fram och utvärderats med för och nackdelar. En översiktlig kostnadskalkyl har gjorts som visar på att det blir svårt att designa roder som en större enhet för additiv tillvekning som är ekonomiskt jämförbart med dagens tillverkingsmetoder. De viktigaste framgångsfaktorerna för additiv tillverkning är ökad skrivarhastighet, kvalificering av tillverkningsprocesserna och CAD stöd för ingenjörerna.

<p>Extrusion Deposition Additive Manufacturing (EDAM) is a process in which fiber-filled thermoplastic polymers are mixed and melted in an extruder and deposited onto a build plate in a layer-by-layer basis. Anisotropy caused by flow-induced orientation of discontinuous fibers along with the non-isothermal cooling process gives rise to internal stresses in printed parts which results in part deformation. The deformation and residual stresses can be abated by modifying the fiber orientation in the extrudate to best suit the print geometry. To that end, the focus of this research is on understanding the effect of fiber orientation state and fiber properties on effective properties of the printed bead and the final deformation of a part. The properties of three different orientation tensors of glass fiber-filled polyamide and carbon fiber-filled polyamide were experimentally and virtually characterized via micromechanics. A thermo-mechanical simulation framework developed in ABAQUS© was used to understand the effects of the varying fiber orientation tensor and fiber properties on the final deformation of printed parts. In particular, a medium-size geometry that is prone to high deformation was simulated and compared among the three orientation tensors and two material systems. This serves to be a good preliminary study to understand microscopic properties induced deformations in EDAM.</p>

<p>High pressure die casting is an industrial metal casting process used to manufacture goods for use in many aspects of society. Within this manufacturing process, the tooling is subjected to chemical attack from molten aluminum while also being responsible for heat removal during solidification. The purpose of this study is to develop and test materials that allow the tools to better withstand the chemical attack, and to develop design rules to guide the use of additive manufacturing for improving the heat exchange function of by way of conformal cooling.</p> <p> </p> <p>Within the material studies, a gooseneck with a niobium lining was developed to allow the successful implementation of hot chamber aluminum die casting. In addition, a manufacturing plan is described that will allow the niobium gooseneck design to be easily sourced by die casting companies. The material studies also included dunk testing of several coatings, including a plasma assisted chemical vapor deposition silicon doped diamond like carbon (PACVD Si-DLC). The Si-DLC coating performed the best in the dunk testing as compared to bare and nitrocarburized tool steel, and a number of other coating architectures.</p> <p> </p> Within the study of additively manufactured conformal cooling design, a finite difference model is developed that allows a simulated experiment that produced a number of useful equations that guide the design of die casting tooling. During the development of the models, it was discovered that little is known regarding the friction factors of additively manufactured steel pipes, so a factorial experiment was employed to empirically determine said friction factors. Charts allowing design engineers to quickly determine pressure drops and heat transfer coefficients of conformal cooling designs was produced as well.<br>

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